Patio heater underneath polycarbonate pergola roof

I reckon you'll melt it!

Might be ok with a gas table patio heater, but a full height gas patio heater throws out a lot of kw's, but a lot of it is radiant heat.

Polycarbonate has a glass transition temperature of about 147 °C (297 °F), so it softens gradually above this point and flows/ melts above about 155 °C (311 °F).

 

I suspect chimineas will certainly have too much heat coming straight out the top for your roof, as they also tend to be quite tall and/or have legs. They need a flue of a certain length to make them work - 'draw' properly.

Well-designed gas patio heaters might be ok provided they don't get too close to the roof - as you say, they have a deflector above them to aim the heat downwards. Cheap versions might not be so well designed so could be very hot above. All should come with guidelines so no guesswork required.

Again, regarding CO, they will almost certainly have caution against use in confined/enclosed spaces, so it will come down to chust how open your area is.

What is the size of your decking, and the sizes of the open sides?

I suspect it will not really be an issue since the area is effectively 'open', but you can't be too careful.

If this is a really nice useful area that you will use a lot and you don't mind spending a little more on it, an option is always to fit a flue to your chosen heater - open fireplace, chiminea or whatever - to direct the heat and fumes above the roofing.

Or, there must be some other solutions such as electric patio heaters (similar to the gas type - a heater mounted on a deflector and suspended on a chain above http://www.primrose.co.uk/-p-22420....showPLA=true&gclid=CPT_2t7EicUCFa7JtAodxEkAtw ) - or, if you really want to show off, a firepit... http://www.todayspatio.com/store/ou...4-rectangular-coffee-table-with-fire-pit.html

 

If you have two walls, making a partly enclosed space,then there is no breeze going through, so I suppose carbon monoxide could/will build up.

Some of the bigger heaters are up to 60,000 BTU.

 

The hot products will still rise and CO levels will be higher, I would stick to a woolly jumper myself

 

Always electric halogen/ infared patio heaters.
2kW) IR heater uses approx 18p per hour in electricity.

http://www.heat-outdoors.co.uk/shop/help-desk/useful-articles/greener-outdoor-heating.html

 

That's the obvious solution here. And I bet leccy will be cheaper to run than a gas cylinder too.

Chust flick a switch, man...

 

That's pretty 'open'! Is there a supporting post in that open corner?

Ok, possible heat damage? I dunno - but that should be an easy one to work out in advance - read the instructions on the gas heaters...

Cimineas? Well, annoying smoke will likely be an issue even if not the flue temp.

CO build up? That will remain an unknown, I suspect. I'd have thought that the gentlest breeze would clear away everything, but what if there's a still 'airless' evening?

Even so, if CO is heavier than air (like CO2) it'll slink over, through and out of the patio floor.

I'd have thought that the chances of any CO poisoning must be incredibly small.

But that's chust a 'thought'.

 

Choose, just for research, a good quality gas patio heater. Email the manufacturers/importers and give them your scenario - see what they say.